A variety of methods are suggested for detecting the amount of PM (particulate matter) deposited in an exhaust passage in an internal combustion engine.
PTL 1 discloses a device which includes a plurality of particulate sensors mounted in an exhaust passage and respectively including heaters for burning off PM deposited on the plurality of particulate sensors. Time required for the regeneration is compared among the plurality of particulate sensors, thus allowing detection of abnormal conditions of the particulate sensor.
PTL 2 discloses a device in which the timing of performing the regeneration process is determined on the basis of an exhaust pressure in the upstream side of a filter in order to perform the regeneration treatment for heating the filter collecting the PM for burning, and the regeneration timing is not determined when the rate of a change in exhaust temperature with time is negative. In the device, avoiding the influence of a change in exhaust temperature makes it possible to avoid degradation of the accuracy in the measurement of the degree of clogging with PM on the basis of an exhaust pressure.